Various handwriting input devices have been developed. Each of them uses an input unit, such as a pen-input tablet or a touch panel, to input handwritings of handwritten characters and letters on the display screen of a computer. Such a handwriting device receives an input of information in the form of a sequence of coordinate points or the like as a handwriting from the input unit of the pen-input tablet, the touch panel, or the like using input means, such as a stylus pen or a fingertip. Then the handwriting input device displays the hand-written character patterns based on the input sequence of coordinate points on the display unit of a monitor or the like. Displaying hand-written characters on the display unit in this way leads to an advantage of allowing the user to perform handwriting input while visually confirming the input contents.
Such a handwriting input device is applied to a computer system to perform password authentication by character recognition of a handwriting and then perform authentication processing, such as authentication of a writer. The authentication processing determines a writer based on the shape of an input handwriting and the speed and acceleration of writing characters. However, when a handwriting input device is used for the authentication processing, or the like, a handwriting displayed on the display unit at the time of inputting hand-written characters may lead to visual recognition of input contents by anybody else, causing a decrease in safety.
As a method for solving such disadvantages, a method that does not display a handwriting at all may be considered. However, such a method makes the user difficult to visually recognize the handwriting. Thus, the user is also difficult to recognize, for example, whether an input is actually received, collectively recognized, or the like.
Therefore, a technology is provided for deleting a handwriting after passing a predetermined time from the input of hand-written characters using a handwriting input device (see, for example, Japanese Patent No. 3105100).